Device having a glow-discharge tube and glow-discharge tube intended for such device



Jan. 8, 1963 s. M. FROU E'Al. 72, 5

DEVICE HAVING A GLOW-DISCHARG BE AND GLOW-DISCHARGE TUBE INT VICE ENDEDF0 UCH DE Filed Nov. 14, 1960 2 Sheets-Sheet 1 INVENTOR SIMON FROUHS JANSE LING AGT Jan. 8, 1963 S. M. FROUWS ETA]. DEVICE HAVING AGLOW-DISCHARGE TUBE AND GLOW-DISCHARGE TUBE INTENDED FOR SUCH DEVICEFiled NOV. 14, 1960 2. Sheets-Sheet 2 INVENTOR SIMON M.FROUUS JANHORSEQING 3,072,825 DEVICE HAVING A GLOW-DISCHARGE TUBE ANDGLOW-DISCHARGE TUBE INTENDED FOR SUCH DEVICE 7 Simon Mari Frouws and JanHorseling, Eindhoven, Netherlands, assignors to North American PhilipsCompany, Inc., New York, N.Y., a corporation of Delaware Filed Nov. 14,1960, Ser. No. 69,109 Claims priority, application Netherlands Dec. 8,1959 4 Claims. (Cl. 315269) This invention relates to devices having aglow-discharge tube containing a cold non-activated cathode and anigniting anode near the cathode, the anode being substantiallysurrounded by a screen. It also relates to glow-discharge tubes intendedfor such devices.

Glow-discharge tubes are already known in which the anode screen isconnected to the cathode through a highohmic resistor and wherein due tothe small distance between the anode'screen and the anode, which is nomore than a few times the free length of the path of the electrons inthe filling gas of the tube, only a very weak discharge suflicient forsuppressing delays in ignition can occur between the anode and the saidscreen. Since the anode screen is connected to the cathode, such a tubeis not suitable for alternating voltage between the main electrodes.

Tubes are also known in which the potential applied to the anode screenis not constant and wherein steps are taken for suppressing leakagecurrents to the anode screen, for example by preventing the occurrenceof atomised layers on the insulator supporting the screen. Such tubesare suitable for alternating voltage between the main .electrodes. Inorder to obtain sufiicient voltage stability of the tube in the forwarddirection, the

However, in order to derive a negative potential for the igniting anodefrom. the mains, it is necessary to interpose a transformer.

An object of the invention is to provide a device having aglow-discharge tube in which ordinary mains voltages with the voltagevariations occurring therein can be used between the anode and thecathode, without objection, whilst nevertheless sufiicient sensitivityto ignition by means of a positive igniting anode can be obtained.

According to the invention in a device having a glowdischarge tubecontaining a cold non-activated cathode and an igniting anode near thecathode and'wherein the anode is substantially surrounded by a screen asecond screen electrode is provided outside the anode screen andconnected through a high-ohmic resistor to the cathode lead, whereas theanode screen is connected through a high-ohmic resistor to the anodelead, at least one of the two screens having a projection directedtowards the other screen so that for the alternating operating voltagebetween the main electrodes a Weak discharge occurs between the twoscreens at a distance from the main discharge path such that delays inignition in the discharge path between the igniting anode and thecathode can be prevented, but decreases in igniting voltage in the maindischarge path in one of the two directions do not occur.

Due to the high-ohmic resistors through which the screens are connectedto the main electrodes and the guard discharge which occurs between thetwo screens, a voltage distribution between the anode, cathode and twoscreens is brought about in the tube to enhance the voltage stabilitythereof.

Preferably, in a tube intended for a device according to the invention,the anode screen is so arranged relative Patented Jan. 8, 1963 to theanode that straight lines which do not intersect the screen can be drawnonly between a portion of the surface of the cathode and the anode,whereas such lines cannot be drawn at all between the anode and thatportion of the cathode to which the auxiliary discharge applies, orbetween the anode and the igniting anode, in this case, the auxiliarydischarge between the two screens preferably takes place on that side ofthe anode screen which is remote as far as possible from the aperturefor passing the main discharge.

In order that the invention maybe readily carried into eifect, it willnow be described in detail, by way of example, with reference to theaccompanying diagrammatic drawings, in which:

FIGURE 1 is an axial section of the bulb of a discharge tube with theelectrodes viewed from the side;

FIGURE 2 is a plan view of the electrodes;

FIGURES 3 and 4 show two sections taken along the lines IIIIII andIV--IV of FIGURE 2, and

FIGURE 5 shows a simple circuit arrangement.

Referring now to FIGURES l to 4, a bulb 2 is sealed to a base 1 of thetube. A cathode 3 consists of a buckled molybdenum sheet which issecured to three supporting wires. An anode 4, which is made of nickel,is wire-shaped and surrounded by an anode screen 5. The cathode 3 has asharply-pointed projection 6 and opposite thereto is an auxiliary anode7 which is made of molybdenum strip. The anode screen 5 is surrounded bya buckled screen 8 which, like the anode screen 5, is made of nickel.The screen 8 carries a projection 9 which extends up to a distance of0.5 mm. from the anode screen 5. The distance between the auxiliaryanode 7 and the projection 6 of the cathode is 0.2 mm. The relativearrangement of the anode and the projection of the cathode can beclearly seen from FIG. 3. The relative arrangement of the cathode-screenprojection 9 and the anode screen can be seen from FIGURE 4. The fillingof the tube consists of neon of mm. of mercury column. To prevent delaysin the ignition of the guard discharge between the projection 9 and theanode screen 5, one wing of the screen 8 has provided on it a smallamount of fine pulverulent titanium 10 having absorbed in it theradio-active material tritium to an amount of about l C. A nickel pole11 serves as an anode for atomising the peak 6 and the auxiliary anode 7by sputtering in a glow discharge.

In FIGURE 5, the tube is indicated by 12, the cathode by 13, the anodeby 14, the anode screen by 15, the cathode screen by 1-8, the projectionof the cathode by 16 and the auxiliary anode by 17. The cathode screen18 'is connected through a resistor 19 of 10 megohrns to the cathodelead and the anode screen 15 is connected through a resistor 20 likewiseof 10 megohrns to the anode lead. The tube is fed from analternating-voltage source 21 of 220 volts.

Branched from the'anode lead, through a sensitive element 22, is theconnection to the igniting anode 17, which includes a resistor 23 whichis also connected to the cathode through a capacitor 24. The sensitiveelement 22 comprises a photo-resistor of cadmium sulphide. Thephoto-resistor has a very high resistance if not radiated by light and alowresistance upon radiation. Itv

light falls on the resistor 22, the voltage set up at the igniting anode17 during the positive phase is such that the auxiliary discharge andhence the main discharge in trol by the auxiliary anode at analternating voltage of volts from the source 21, whilst ignition stilldoes not occur at 275 volts without control voltage at the ignitinganode 17 r What is claimed is:

1. A glow discharge device comprising a glow discharge tube including anenvelope containing an ionizable gaseous medium, a cold, non-activatedcathode, an anode, and an igniting anode all within said envelope, saidanode and cathode electrodes defining a main discharge path therebetweenand said igniting anode and said cathode defining an auxiliary dischargepath therebetween, a tubular screen electrode substantially surroundingsaid anode and interposed between the cathode and igniting anode, and asecond screen electrode positioned on the side of said tubular screenelectrode remote from the anode, means including a resistor connectingsaid second screen electrode to said cathode, means including a resistorconnecting said tubular screen electrode to said anode, and means toapply a cyclic alternating potential between the cathode and anode, atleast one of said screen electrodes having'a projection directed towardsthe other screen electrode whereby with the alternating potentialapplied between the cathode and anode a relatively weak discharge occursbetween the two screen electrodes at a distance from the main dischargepath at which delays in ignition in the auxiliary discharge path areprevented without a decrease in igniting potential in the main dischargepath. 4

2. A glow discharge device comprising a glow-discharge tube including anenvelope containing an ionizable gaseous medium, a cold, non-activatedcathode, an

charge tube including an envelope containing an ionizable gaseousmedium, a cold, non-activated cathode, an anode, and an igniting anodeall within said envelope, said anode and cathode electrodes defining amain discharge path therebetween and said igniting anode and saidcathode defining an auxiliary discharge path therebetween, a tubularscreen electrode substantially surrounding said anode and interposedbetween the cathode and igniting anode, and a second screen electrodepositioned on the side of said tubular screen electrode remote from theanode and spaced from the main discharge path, means including aresistor connecting said second screen electrode to said cathode, meansincluding a resistor connecting said tubular screen electrode to saidanode, and means to apply a cyclic alternating potential between thecathode and anode, at least one of said screen electrodes having aprojection directed towards the other screen electrode whereby with thealternating potential applied between the cathode and anode a relativelyweak discharge occurs between the two screen electrodes at a distancefrom the main discharge path at which delays in ignition in theauxiliary discharge path are prevented without a decrease in ignitingpotential in the main discharge path.

anode, and an igniting anode all within said envelope, i

said anode and cathode electrodes defining a main discharge paththerebetween and said igniting anode and said cathode defining anauxiliary discharge path therebetween, a cylindrical screen electrodesurrounding said anode and interposed between the cathode and ignitinganode, and a second screen electrode positioned on the side of saidcylindrical screen electrode remote from the anode and being shieldedtherefrom by said cylindrical screen electrode, means including aresistor connecting said second screen electrode to said cathode, meansincluding a resistor connecting said cylindrical screen electrode tosaid anode, and means to apply a cyclic alternating potential betweenthe cathode and anode, at least one of said screen electrodes having aprojection directed towards the other screen electrode whereby with thealternating potential applied between the cathode and anode a relativelyweak discharge occurs between the two screen electrodes at a distancefrom the main discharge path at which delays in ignition in theauxiliary discharge path are prevented without a decrease in ignitingpotential in the main discharge path.

3. A glow discharge device comprising a glow dis- 4. A glow dischargetube comprising an envelope containing an ionizable gaseous medium, acold, non-activated cathode, an anode, and an igniting anode all withinsaid envelope, said anode and cathode electrodes defining a maindischarge path therebetween and said igniting anode'and said cathodedefining an auxiliary discharge path therebetween, a tublular screenelectrode substantially surrounding said anode and interposed betweenthe cathode and igniting anode, a second screen electrode positioned onthe side of said tubular screen electrode remote from the anode andspaced from the main discharge path, at least one of said screenelectrodes having a projection directed towards the other screenelectrode whereby with an alternating potential -i applied between thecathode and anode a relatively weak discharge occurs between the twoscreen electrodes at a distance from the main discharge path at whichdelays in ignition in the auxiliary discharge path are prevented withouta decrease in igniting potential in the main dis- 1 charge path.

References Cited in the file of this patent UNITED STATES PATENTS2,444,072 Stutsman June 29, 1948 2,607,021 Von Gugelberg Aug. 12, 1952,2,736,840 Tosswell Feb. 28, 1956

1. A GLOW DISCHARGE DEVICE COMPRISING A GLOW DISCHARGE TUBE INCLUDING ANENVELOPE CONTAINING AN IONIZABLE GASEOUS MEDIUM, A COLD, NON-ACTIVATEDCATHODE, AN ANODE, AND AN IGNITING ANODE ALL WITHIN SAID ENVELOPE, SAIDANODE AND CATHODE ELECTRODES DEFINING A MAIN DISCHARGE PATH THEREBETWEENAND SAID IGNITING ANODE AND SAID CATHODE DEFINING AN AUXILIARY DISCHARGEPATH THEREBETWEEN, A TUBULAR SCREEN ELECTRODE SUBSTANTIALLY SURROUNDINGSAID ANODE AND INTERPOSED BETWEEN THE CATHODE AND IGNITING ANODE, AND ASECOND SCREEN ELECTRODE POSITIONED ON THE SIDE OF SAID TUBULAR SCREENELECTRODE REMOTE FROM THE ANODE, MEANS INCLUDING A RESISTOR CONNECTINGSAID SECOND SCREEN ELECTRODE TO SAID CATHODE, MEANS INCLUDING A RESISTORCONNECTING SAID TUBULAR SCREEN ELECTRODE TO SAID ANODE, AND MEANS TOAPPLY A CYCLIC ALTERNATING POTENTIAL BETWEEN THE CATHODE AND ANODE, ATLEAST ONE OF SAID SCREEN ELECTRODES HAVING A PROJECTION DIRECTED TOWARDSTHE OTHER SCREEN ELECTRODE WHEREBY WITH THE ALTERNATING POTENTIALAPPLIED BETWEEN THE CATHODE AND ANODE A RELATIVELY WEAK DISCHARGEOCCURES BETWEEN THE TWO SCREEN ELECTRODES AT A DISTANCE FROM THE MAINDISCHARGE PATH AT WHICH DELAYS IN IGNITION IN THE AUXILIARY DISCHARGEPATH ARE PREVENTED WITHOUT A DECREASE IN IGNITING POTENTIAL IN THE MAINDISCHARGE PATH.